Sealing strips of this type are used not only in the field of vehicle construction but also in numerous other fields of machine and apparatus construction which are always faced with the problem of sealing a gap between two parts which are movable relative to each other in that the sealing strip is connected to one of the two parts and in the sealing condition is pressed elastically so as to lie against the other part.
In the case of a corresponding embodiment of the sealing strip, the connection to one part can be accomplished in a positive-locking manner by means of an elastic locking arrangement—however, an adhesive connection is frequently provided. For this purpose, the sealing strip normally consists of a layer which imparts the actual sealing effect and which is coated on one side with an adhesive layer, wherein for its part the adhesive layer is covered by a cover sheet.
All of these layers are tailored to one another in terms of their material and are geared in function towards the sealing effect which is to be achieved. In particular, the cover sheet is arranged in such a manner that there is no adhesive connection to the covered adhesive, so that the cover serves to keep the adhesive in an inactive yet usable state once the cover sheet has been removed. Where these conditions prevail, it is basically possible to use any physically hardening or chemically reacting, cold- or hot-curing adhesive.
To facilitate handling during assembly, it is known to provide sealing strips of this type with tear-off tabs which render it possible to take hold of the cover sheet manually to remove it just before assembly. In order to make the sealing strip ready for installation, it must first be cut in its original state to the required length and then be provided with at least one tear-off sheet of this type which in this case is typically adhered to the outer side of the cover sheet.
Sealing strips of this type are widely used in vehicle construction, so that the material requirement for providing the tear-off tabs, which consist e.g. of polyethylene, is considerable. Added to this are the operating costs incurred by connecting the tabs to the sealing strips.
These sealing strips are frequently installed under spatially restricted conditions, in particular at sites to which access cannot be gained easily. Since the substance of the said cover sheet is selected on the condition that it has only limited, or almost no, suitability for adhesive purposes, the possibility that the connection between the cover sheet and the tear-off tab will be broken cannot be entirely ruled out, so that the assembly procedure can sometimes become extremely laborious since after said connection has been broken the cover sheet must be separated from the adhesive layer in another way.
Against this background, it is the object of the invention to form a sealing strip of the type described in the introduction such that where material usage is reduced considerably, more rationalized working and secure handling are possible during assembly. In the case of this type of sealing strip, this object is achieved by a sealing strip having a removable cover sheet protecting an adhesive layer, wherein the cover layer has a tear thread that passes through it, the tear thread providing an auxiliary means for removing the cover sheet.
Accordingly, it is an aspect of the invention that the auxiliary means which is intended for manually removing the cover sheet is formed by merely a tear-thread which is inserted into the substance of the cover sheet or is anchored therein. The thread is dimensioned and its material selected such that it is suitable for transmitting the force sufficient for removing the cover sheet. The connection between the thread and the cover sheet is also arranged accordingly. In comparison with the prior art set forth in the introduction, this auxiliary means which preferably consists of synthetic material uses considerably less material and operates with a greater degree of reliability owing to a positive-locking connection with the cover sheet. One or even several tear-threads can be provided along the sealing strip.
Preferably, the tear-thread is provided on both ends with planar holding elements. Since the tear-thread passes through the substance of the cover sheet, these planar holding elements simultaneously form anchoring elements which ultimately support the positive connection to the cover sheet. These planar holding elements can be provided, for example, in the form of rectangular platelets but also cross-bars which extend perpendicular to the longitudinal extension of the tear-thread.
The procedure of producing a connection between tear-threads and the cover sheet can be performed in a mechanized manner using press-in or even shoot-in processes. In this manner, it is also possible to check that the tear-thread passes merely through the substance of the cover sheet and not through other layers of the sealing strips.
The layer forming the visible surface of the sealing strip can consist, for example, of rubber or other elastomer which can also be used in a foam-like consistency, whereas the adhesive layer consists of acrylic foam. However, the invention can basically be used for any sealing strips which for assembly purposes are prepared with an adhesive layer covered by a cover sheet, and furthermore irrespective of the adhesive system or material composition of the adhesive layer.
The sealing strip can be provided in a linear but also annular structure for the user and it is equipped in each case with one or several tear-threads. It offers significant advantages over the prior art set forth in the introduction with regard to its production costs, but in particular also with regard to its practical handling properties during assembly.
The invention will be explained in detail hereinunder with reference to the exemplified embodiment illustrated in the drawings and with reference to the exemplified embodiment associated with the prior art.